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Margareta Johansson

Researcher

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Past changes in arctic terrestrial ecosystems, climate and UV radiation

Author

  • Terry V. Callaghan
  • Lars Olof Björn
  • Yuri Chernov
  • Terry Chapin
  • Torben Christensen
  • Brian Huntley
  • Rolf A. Ims
  • Margareta Johansson
  • Dyanna Jolly
  • Sven Jonasson
  • Nadya Matveyeva
  • Nicolai Panikov
  • Walter Oechel
  • Gus Shaver
Show all

Summary, in English

At the last glacial maximum, vast ice sheets covered many continental areas. The beds of some shallow seas were exposed thereby connecting previously separated landmasses. Although some areas were ice-free and supported a flora and fauna, mean annual temperatures were 10-13degreesC colder than during the Holocene. Within a few millennia of the glacial maximum, deglaciation started, characterized by a series of climatic fluctuations between about 18 000 and 11 400 years ago. Following the general thermal maximum in the Holocene, there has been a modest overall cooling trend, superimposed upon which have been a series of millennial and centennial fluctuations in climate such as the "Little Ice Age spanning approximately the late 13th to early 19th centuries. Throughout the climatic fluctuations of the last 150 000 years, Arctic ecosystems and biota have been close to their minimum extent within the most recent 10 000 years. They suffered loss of diversity as a result of extinctions during the most recent large-magnitude rapid global warming at the end of the last glacial stage. Consequently, Arctic ecosystems and biota such as large vertebrates are already under pressure and are particularly vulnerable to current and projected future global warming. Evidence from the past indicates that the treeline will very as it probably advance, perhaps rapidly, into tundra areas, a it did during the early Holocene, reducing the extent of tundra and increasing the risk of species extinction. Species will very probably extend their ranges northwards, displacing Arctic species as in the past. However, unlike the early Holocene, when lower relative sea level allowed a belt of tundra to persist around at least some parts of the Arctic basin when treelines advanced to the present coast, sea level is very likely to rise in future, further restricting the area of tundra and other treeless Arctic ecosystems. The negative response of current Arctic ecosystems to global climatic conditions that are apparently without precedent during the Pleistocene is likely to be considerable, particularly as their exposure to co-occurring environmental changes (such as enhanced levels of UV-B, deposition of nitrogen compounds from the atmosphere, heavy metal and acidic pollution, radioactive contamination, increased habitat fragmentation) is also without precedent.

Department/s

  • Molecular Cell Biology
  • Dept of Physical Geography and Ecosystem Science

Publishing year

2004

Language

English

Pages

398-403

Publication/Series

Ambio: a Journal of Human Environment

Volume

33

Issue

7

Document type

Journal article

Publisher

Springer

Topic

  • Physical Geography
  • Biological Sciences

Status

Published

ISBN/ISSN/Other

  • ISSN: 0044-7447